CLASS — NOAA’S PREMIER ENVIRONMENTAL DATA ARCHIVE

October 28, 2005 — Every day NOAA processes environmental data from a wide variety of sensors deployed on satellites, aircraft, marine buoys and numerous other platforms. Most of the data gets used immediately for critical applications, such as weather forecasting. But what happens to the data after the rainstorm has passed or the sunny day has ended? Does it still have any use or value? The answer is a resounding “Yes!”

Consider an example that illustrates just how valuable this data can be. A weather researcher is working to improve an existing weather model used for predicting where a hurricane will make landfall. By gathering all the available data from previous hurricanes, the researcher can run the new model using the actual starting conditions and then compare the results with what actually happened in the real event. The model can continue to be analyzed and refined in this way until it gives better prediction results. In this example, improved landfall predictions can result in increased safety by evacuating the people in imminent danger and increased savings by not evacuating more people than necessary.

Another example of the value of older data is the climate research focused on longer term events, such as global warming. Some of the most valuable data for this purpose are satellite observations taken over the last three decades. Fortunately, NOAA has a responsibility to ensure that this data remains accessible and is not lost. One important system for archiving past, present and future environmental data is the Comprehensive Large Array-data Stewardship System (also known as CLASS).

At the CLASS Developers Workshop in February 2005, Richard Reynolds, the CLASS Project Manager, explained that “NOAA's National Data Centers and their worldwide clientele of customers look to CLASS as the sole NOAA IT infrastructure project in which all NOAA’s current and future environmental data sets will reside.” CLASS provides permanent, secure storage and safe, efficient transfer between the NOAA National Data Centers and their customers. The customer can access CLASS via a web-based user interface at http://www.class.noaa.gov, which is shown in the figure to the right. CLASS serves as a data archive and distribution system. As a data archive system, CLASS is able to ingest and store the data and maintain data quality. As a data distribution system, CLASS provides access to the data, allowing customers to preview some of the data visually and to place orders for specific data sets.

CLASS is built upon the Satellite Active Archive, an earlier system that first became operational in 1995. The transition from the SAA to the CLASS architecture began in 2001 with the first CLASS operational site at the NOAA Office of Satellite Data Processing and Distribution in Suitland, Md. In April 2004, a second CLASS site became operational at the NOAA National Climatic Data Center in Asheville, N.C. Both sites share the same data catalog and are synchronized in near-real time so that either site can take over in the event of failure of the other. Future plans include moving the Suitland operational site to the NOAA National Geophysical Data Center in Boulder, Colo., in 2006.

CLASS has a wide array of users, consisting of public- and private-sector climatic researchers and weather forecasters. “I’ve found CLASS very useful,” explained WDTV Chief Meteorologist Brandon Butcher, who works at a CBS television affiliate in Bridgeport, W.Va. “I use it to identify weather patterns over certain areas over a period of time. For example, when I track storm systems that develop over the southeast, I can see the patterns and be able to spot future trends by looking at the past data.” Butcher explains that the CLASS data helps him provide a more detailed future forecast because it allows the user to compare current storms to previous ones using their satellite signature data. CLASS users can search and order from 32 types of atmospheric, coastal, ocean and other data products.

Currently, CLASS has about 27,500 registered users. In July 2004, an exit survey was added to CLASS requesting users to specify how they planned to use the data that they had requested in their order. Since that time, CLASS has processed more than 30,000 orders. The exit survey has revealed that 70 percent of the orders were used for science, 13 percent for educational purposes and 10 percent for personal reasons.

For the most part, CLASS is being used for research by scientists, professors and graduate students. Technical Area Lead for CLASS, Constantino Cremidis, points out that most of the current user research deals with climatic studies. Cremidis says that the support of other data types, such as NEXRAD, will result in a greater use of CLASS for weather forecasting. As CLASS is enhanced to support more types of data, and the user interface is modified to satisfy user needs, Cremidis feels that the user profile will become more varied. (Click on NOAA image to the right for a larger view of the CLASS graphic displaying global ocean sea surface temperatures on Sept. 4, 2004. Please credit "NOAA.").

“CLASS represents a capability whose greatest value will accrue to future generations,” said Mike Kalb, meteorologist and chief scientist at Global Science & Technology, Inc. “By systematically preserving environmental data in a scientifically consistent and useable way, it will prove a vital resource to future scientists in assessing climate change 50 or 100 years from now.”

Kalb states that building a long-term data record around day-to-day operationally produced data sets and products has the advantage of being sustainable over decades. “It’s that consistent long-term record that is important — and that is what the NOAA CLASS approach will ultimately become.”

According to Axel Graumann, meteorologist on the Satellite Service Team at NCDC, many users want new tools that will display data in ways that are useful for their research. Also, Graumann said that users “want to know if their software tools will import CLASS data.”

The CLASS archive now holds data from polar-orbiting operational environmental satellites and geostationary operational environmental satellites, although not all the existing historical GOES data (stored on tape) has been imported into CLASS. According to Lisa Weiss, CLASS Operations Manager at NCDC, this older GOES data is currently being ingested into CLASS at a rate of 320 GB per day. Weiss estimates that a total of 70 TB of historical GOES data will be ingested this year. (Click on NOAA image above right for a larger view of the CLASS graphic displaying global aerosol optical thickness on May 12, 2005. Please credit "NOAA.").

CLASS will provide a cost savings to NOAA in development and operations. According to an article published in Government Computer News on May 24, 2004, “by fiscal year 2011 NOAA will have spent $117 million on CLASS development, compared with an estimated cost of $212 million to maintain the status quo of data dissemination — the 10-year total cost to operate individual archive systems would have been more than $400 million, compared with $180 million for CLASS.”

Beyond the cost savings, indirect benefits will result from complying with National Archives and Records Administration policies for data storage and preservation and the ability to handle new data sets.

The future holds many challenges for CLASS. One key challenge that Cremidis foresees is keeping up with new data types and data. Another challenge is to increase the bandwidth and processing power to support larger volumes of data. A third challenge will be to improve the user interface to be more useful — both to scientists who need more sophisticated methods of accessing the data, and to the general public.

Looking to the future, Cremidis sees the need for more system-to-system communication, which would result in CLASS “no longer being an island, but part of a community.”

CLASS is currently both an 24x7 operational system, and a system which has a planned developmental evolution over the next 10 years. The CLASS Project is managed by the NOAA Office of Systems Development in Suitland, Md.

Relevant Web Sites
NOAA Satellite and Information Service

NOAA Satellites

NOAA's Geostationary and Polar-Orbiting Weather Satellites

NOAA National Climate Data Center

NOAA Geophysical Data Center

NOAA Oceanographic Data Center

NOAA National Coastal Data Development Center

Media Contact:
John Leslie, NOAA Satellites and Information, (301) 457-5005